1. Field
The present disclosure generally relates to the field of couplers, and more particularly, to systems and methods for reducing coupling coefficient variation.
2. Description of the Related Art
In certain applications, such as third generation (3G) mobile communication systems, robust and accurate power control under load variation is desired. To achieve this, high directivity couplers are often used with power amplifier modules (PAMs). The couplers directivity is typically limited to 12-18 dB in order to maintain a coupler factor variation, or peak-to-peak error, of between ±1 dB and ±0.4 dB with an output Voltage Standing Wave Ratio (VSWR) of 2.5:1.
However, new multi-band and multi-mode devices, and new handset architectures that use Daisy Chain Couplers to share power between different bands require much higher directivity with a lower coupler factor variation. Achieving such requirements is becoming more difficult as demand for smaller chip packages increases.